l5 On the Colourhig and Morda?tt Property 



water, and fatiivated with potafli. The tnolybdate of potafii 

 beino; ibiiible in a much larger quantity of cold water than 

 the tree niolybdic acid, this acid was united to potafli with 

 a view that a more concentrated folution of it might be ap- 

 plied to the {luff, whichj in regard to linen and cotton, is a 

 matter of great importance. 



A. One part of this folution was diluted with ten or twelve 

 parts of rain water ; and a flired of raw white woollen fluff, 

 and another of white Saxon kerfeymerc, were boiled in it for 

 half an hour. The two flireds affumcd a grayifh green co- 

 lour. Both of them were then cut into Tmall bits, for the 

 purpofe of fubje^ling them to the following experiments ; 



Thefe bits of cloth were put, ift, Into a boiling fo- 

 lution of fulphate ©f zinc very much diluted : 2d, A fimilar 

 folution of acetite of lead : 3d, Another of fulphate of cop- 

 per : 4th, Another of tin in the fulphuric and muriatic acids: 

 5th, Another of fulphate of iron : 6th, Of tin in fimple mu- 

 riatic acid ; 7th, Another of tin in acetous acid : 8th, An- 

 other of tin in nitro-muriatic acid by muriate of ammonia: 

 qth, Into one of cobalt in nitric acid, rendered {lightly mu- 

 riatic by muriate of foda : loth, And into aqueous tin6lure 

 of gall-nuts prepared cold, which communicated to woollen 

 ftuif boiled in it a rullet colour. 



The different pieces, after being boiled for a quarter of an 

 hour in folution of niulybdena, when waflied and dried ex- 

 hibited different {hades. 



B. A flired of white cotton cloth was immerfed, cold, for 

 twelve hours, in a part of the folution of molybdate of pota{li 

 much diluted ; and it was then removed to a diluted folution 

 of tin in a mixt'.ire of the fulphuric and muriatic acids. The 

 Huff, which had not changed its colour in the folution of 

 inolybdena, aflunied a briglit blue colour fomewhat dirty. 



The above two pieces ot cloth which were treated with the 

 folutions of tin exhibited this peculiar pha;nomenon, that 

 on the edge, when cut, they were of a darker and purer blue 

 than externally. Another circuni{tance, no lefs remarkable, 

 is, that thefe ccdours experienced from the light an cffcdf con- 

 trary to ihat prf)duced on vegetable colours, which lofe their 

 colour by expofure to the fun; while that of molybdena ac- 

 quires a double degree of intenfity. Tiic green (liades gene- 

 rally paffcd to 1)1 1 e; but after fonie time refumed in the {hade, 

 or when expofcd to the moift atmofphere, their primitive 

 colour. 



However fatisfatlory thefe refults might be, M. Jaeger 

 carried his refearches (till further, and endeavoured to obtain 

 colours better defined, and brighter; and particularly pure 



blue 



